Several behaviors associated with hyperactivity--namely problems of attention, activity level, and impulsivity--have clear detrimental effects on a child's classroom, family and social life; they have a relatively high prevalence but are amenable to some extent to treatment. Therefore, an understanding of their early development and stability is important for a variety of reasons. This project is designed to compare two groups of infants with respect to the incidence and stability of these behavioral dimensions across the first 3 1/2 years. High-risk preterm and normal fullterm infants (100 each) drawn from the same general population will be tested periodically on measures selected to index attention, activity level, and impulsiveness. Measures at 12 months will be based on spontaneous behavior with objects and responses to a barrier between the infant and a desirable object. Measures at 24 months will be based on spontaneous behavior with multiple objects and on behavior to delayed response tasks. In addition, the Bayley Developmental Scales will provide at each age both an index of overall developmental level and two tasks which further tap the particular behavioral dimensions of concern. A scale based on direct observation will also be administered at each age to assess the parent-child interaction and to facilitate plans for future intervention. At 3 1/2 years, the measures will be preschool adaptations of the Matching Familiar Figure Test, the Embedded Figures Test and the Draw-a-Line Slowly Test. These particular outcome measures have selected because they predict test and classroom behavior at older ages moderately well. If individual stability can be demonstrated, our measures may provide a basis for the development of diagnostic tools for early identification of extreme or deviant behavior. Such early identification would permit both early intervention to prevent some of the negative social and educational consequences of hyperactivity and more direct exploration of the origins and mechanisms underlying the behavioral disorder.